Measurement of gamma rejection of solid state neutron sensors to maximise neutron and minimise gamma sensitivities

“我们公司已经投资开发了两种主要类型的新型固态中子传感器，并获得了商业吸引力。它们商业化的一个障碍是缺乏它们在以高强度伽马辐射为主的“混合”辐射领域表现的硬数据。这是典型的核清理场景。我们对这个项目的愿景是我们获得传感器的设计规则和硬数据，量化我们的碳化硅中子传感器在高强度伽马场中的中子特异性。关键目标是了解伽马射线的哪个能量范围会干扰我们的传感器，干扰到什么程度，我们是否可以通过屏蔽去除这些伽马信号，以及简单屏蔽的放置是否会产生二次辐射，这是否比未屏蔽的通量对传感器的影响更大。一旦我们了解了我们最需要屏蔽的能量，我们希望最终测试一个现实的“套件”，它完全代表了轻型遥控中子场测量仪器的一部分。我们的重点将放在伽马辐射对我们的电子设备、传感器的影响，以及整个传感器+信号链在非常高的伽马光子密度下返回有用中子计量的能力上。我们希望能够在能量高于100keV的背景下，以1n /cm2/秒的速度探测到高达8%的热中子。我们想知道我们的中子传感器离“伽马盲”有多近。我们相信我们的硅AT和碳化硅HT系列异质二极管中子传感器是唯一可用的固体探测器，其中块状中子反应材料构成了探测器结构的一部分。这种结构使我们的设备的探测效率大约是任何其他固态热中子探测器的两倍。我们使用的中子反应层产生带电粒子，这些带电粒子总能在薄的敏感区被探测到。这种“薄度”降低了伽马捕获概率。这就是为什么我们相信我们的设备将显示出非常高的伽马拒绝比。我们的传感器在商业上是创新的，因为它们可以在本质安全、重量轻、功耗低、坚固的封装中实现高效率的热中子探测。”

"Our company has invested in the development of two main types of novel solid state neutron sensors and which are gaining commercial traction. An obstacle to their commercialisation is lack of hard data on their performance in ""mixed"" radiation fields dominated by high intensity gamma radiation. This is typical of the nuclear cleanup scenario. Our vision for this project is that we attain design rules and hard data for the sensors which quantify the neutron specificity of our silicon carbide neutron sensors in high intensity gamma fields.The key objectives are to learn which energy ranges of gamma rays interfere with our sensors, and to what extent, whether we can remove those gamma signals by shielding, and whether placement of simple shielding gives rise to secondary radiation which affects the sensors more than the unshielded flux. Once we have learned which energies we most need to shield against, we wish to finally test a realistic ""kit"" which fully represents part of a lightweight remote controlled neutron field survey instrument.Our concentration will be on the effect of gamma radiation on our electronics alone, on our sensors alone, and the ability of the whole sensor + signal chain to return useful neutron metrology in the presence of a very high gamma photon density. We hope to be able to detect up to 8% of thermal neutrons at 1 n/cm2/sec against a background of 1e10 gammas/cm2/sec at energies above 100keV. We want to know how close to ""gamma blind"" our neutron sensors are.We believe our silicon AT and silicon carbide HT series heterodiode neutron sensors are the only solid state detectors available where bulk neutron reactive material forms part of the detector structure. This configuration gives our devices approximtely double the detection efficiency of any other solid state thermal neutron detector. The neutron reactive layer we use generates charged particles which can be always be detected in a thin sensitive region. That ""thinness"" reduces the gamma capture probability. This is why we believe our devices will show a very high gamma rejection ratio .Our sensors are commercially innovative because they allow high efficiency thermal neutron detection in an intrinsically safe, light weight, low power, robust package."